FIG. 3 is a schematic view of a conventional exercise therapy device as disclosed, for example, in JP 62-46193 B. As shown in FIG. 3, in the conventional exercise therapy device, there are provided a pulley 1 connected with pedals 2 to be depressed by the exerciser and a motor 7 for imparting a load to the pedals 2. Between the pulley 1 and the motor 7, there is provided a pulley 3. A belt 4 is looped around the pulley 1 and the pulley 3. Further, a pulley 5 is provided beside the pulley 3. The pulley 3 and the pulley 5 share the same rotation shaft. A belt 6 is looped around the pulley 5 and the motor 7. Magnets 8 and 9 are mounted to the pulley 1 and the pulley 5, respectively. Further, there are provided Hall elements 10 and 11 for detecting the magnets 8 and 9, respectively. That is, the Hall elements 10 and 11 are situated such that when the magnets 8 and 9 rotate with the pulley 1 and the pulley 5 to reach predetermined positions (the lowest positions of FIG. 3), they are opposed to the Hall elements 10 and 11, so upon each rotation, the magnets 8 and 9 are detected by the Hall elements 10 and 11, whereby it is possible to detect the number of times that each of the pulley 1 and the pulley 5 has rotated. Connected to the Hall elements 10 and 11 is a computer 12, to which signals from the Hall elements 10 and 11 are input, whereby the RPM (Revolution Per Minute) (or the number of revolution) of each of the pulley 1 and the pulley 5 is calculated. Connected to the computer 12 is a load control device 13 for controlling the motor 7, and the load of the motor 7 is controlled based on the RPM supplied from the computer 12.
Next, the operation of the device will be described.
The rotation of the pedals 2 is transmitted to the pulley 5 through the belt 4 looped around the pulley 1 and the pulley 3 to thereby effect an increase in speed, and is further transmitted to the motor 7 through the belt 6. Upon each rotation of the pulley 1 and the pulley 5, the Hall elements 10 and 11 output pulse signals to the computer 12. The computer 12 calculates the number of the pulse signals, and outputs it to the load control device 13. The load control device 13 determines the RPM based on the number of pulse signals to thereby control the load of the motor 7. Further, it is possible to detect the phase angle of the pedals 2 from the RPM, so also when the load is to be set in correspondence with the rotating angle position of the pedals 2, it is possible to effect load setting for each rotating angle position of the pedals 2 by using the RPM.
In the conventional exercise therapy device constructed as described above, at the start of an exercise therapy, the exerciser is required to exert a force larger than a frictional load of a drive system of the exercise therapy device before exerciser can start depressing the pedals 2. Thus, when the strength with which the exerciser depresses the pedals 2 is extremely low, the exerciser receives an abrupt load at the start of the exercise therapy.
It should be noted, however, that when an exercise therapy is to be performed, in particular, on an exerciser whose muscular strength (e.g., the strength of quadriceps femoralis and coxal extensor group) has been markedly reduced, a patient with a heart disease, a patient with a cerebrovascular disorder, or an aged person, it is necessary for the pedal rotating motion to be executed with a particularly small load.
In this way, in the conventional exercise therapy device, at the start of an exercise therapy, the exerciser is required to exert a force equal to or larger than the frictional load of the drive system before he or she can cause the pedals to begin to rotate. Thus, in a case in which an exerciser whose muscular strength has been reduced, such as a physically handicapped person or an aged person, performs exercise with the exercise therapy device, there is a problem in that the pedal load at the start of the operation constitutes a considerable load for the exerciser.